21098781542281 has 9 divisors (see below), whose sum is σ = 21188532811341. Its totient is φ = 21009408906444.

The previous prime is 21098781542273. The next prime is 21098781542291. The reversal of 21098781542281 is 18224518789012.

The square root of 21098781542281 is 4593341.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21098781542281 - 2³ = 21098781542273 is a prime.

It is a super-2 number, since 2×21098781542281² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21098781542291) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1097798890 + ... + 1097818108.

Almost surely, 2^{21098781542281} is an apocalyptic number.

21098781542281 is the 4593341-st square number.

21098781542281 is the 2296671-st centered octagonal number.

It is an amenable number.

21098781542281 is a deficient number, since it is larger than the sum of its proper divisors (89751269060).

21098781542281 is an frugal number, since it uses more digits than its factorization.

21098781542281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38916 (or 19458 counting only the distinct ones).

The product of its (nonzero) digits is 5160960, while the sum is 58.

The spelling of 21098781542281 in words is "twenty-one trillion, ninety-eight billion, seven hundred eighty-one million, five hundred forty-two thousand, two hundred eighty-one".